B4 - community level systems Flashcards
what are abiotic factors?
the non-living factors of an ecosystem, e.g. temperature or light intensity
what is aerobic decomposition?
organisms break down dead or decaying matter (decompose) in the presence of sufficient oxygen
what is anaerobic decomposition?
organisms carry out decomposition in the absence of oxygen producing carbon dioxide and methane gas; this usually happens in waterlogged soils
what is biomass?
the mass of all the living material present in a particular area or particular organism
what are biotic factors?
the living factors of an ecosystem, e.g. food availability or pathogens
what is the carbon cycle?
the cycle through which carbon (in the form of carbon dioxide) moves between the environment and living organisms; it involves respiration, photosynthesis, combustion and decomposition
what is combustion?
the process by which organic matter is burnt to release energy as well as carbon dioxide and water; it is part of the carbon cycle
what is a community?
all the populations of different species that are living in a habitat together
what is competition?
when different organisms compete for the same resources (e.g. food, shelter and mates) in an ecosystem; it limits population size
what is compost?
dead or decaying matter that is often used as fertiliser for crops
what is a decomposer?
an organism that feeds on dead and decaying matter
what is decomposition?
the process of breaking down dead material into simple organic matter; the decomposition rate is influenced by water availability, oxygen availability and temperature
what is an ecosystem?
the community of organisms and non-living components of an area and their interactions
what is egestion?
the removal of undigested food from the body as faeces
what is excretion?
the removal of metabolic waste from the body
what is a food chain?
shows the feeding relationships between organisms and the resultant biomass transfer
what is a habitat?
the place where plants, animals and other living organisms live
what is interdependence?
the dependence of organisms on each other in order to survive
what are microorganisms?
very small organisms that are involved in the recycling of materials in an ecosystem; they can convert carbon into carbon dioxide which is then released into the atmosphere; they also return mineral ions to the soil
what is a host?
the organisms on/in which the parasite lives
what is mutualism?
the interaction between two organisms where both benefit as a result of their relationship
what is a parasite?
an organism which feeds on or in a host organism at the expense of the host
what is parasitism?
the interaction between two organisms where only one organism, the parasite, benefits whilst the host cell does not
what is precipitation?
a part of the water cycle where water returns to land in the form of rain, snow or hail
what is predation?
a biological relationship in which a member of one species consumes the member of another species
what is a predator?
a consumer that preys on and eats other animals
what is prey?
a consumer that is eaten by a predator
what is a primary consumer?
an organism that cannot produce its own food, so must obtain energy by feeding on the producer; they are herbivores which consume at trophic level two of a food chain
what is a producer?
an organism that makes its own food, usually via photosynthesis
what is a pyramid of biomass?
a table showing the dry mass of living material at each trophic level in a food chain; this table forms the shape of a pyramid
what is a secondary consumer?
an organism that cannot produce its own food so must obtain its energy by feeding on the primary consumer; they are carnivores which consume at trophic level three of the food chain
what is a species?
a group of organisms that can interbreed and produce fertile offspring
what is a water cycle?
the cycle of water moving between the environment and living organisms; it involves:
- precipitation
- condensation
- transpiration
- biomass transfer
- evaporation
what is a population?
all the members of a single species that live in a particular habitat
what are some examples of biotic factors?
- organic matter
- living things
- oysters
- blue crabs
- zooplankton
- phytoplankton
- jellyfish
- disease
- competition (between living organisms)
what are some examples of abiotic factors?
- climate
- non-living things
- sunlight
- temperature
- nutrient enrichment
- humidity
- soil
what are some physical factors?
- carbon dioxide
- water
- temperature
- oxygen
- nutrients
- light
how is temperature measured?
thermometer or temperature probe
how are nutrients and soil pH measured?
chemical analysis/indicator paper
how is the amount of light measured?
light meter or light sensor
how is water measured?
rain gauge/dehydrate soil sample
how is oxygen measured?
gas probe
how is carbon dioxide measured?
gas probe
what is the range?
the difference between the lowest and highest values
give one way in which an increase in temperature affects organisms
enzyme activity would increase until it begins to denature; increase enzyme activity/metabolism
what are the names for each trophic level?
- producer
- primary consumer
- secondary consumer
etc
are all producers plants?
anything that can trap initial energy (usually photosynthesising)
e.g. photosynthetic bacteria, chemotrophic bacteria, algae
what features do predators have to help them?
- eyes set forward
- sharp teeth/beak/claws
- good eye sight/hearing/sense of smell
- camouflage/stealth
what features do prey have to help them?
- eyes at the side of head
- large eyes/good sense of smell
- camouflaged
- can be nocturnal
- powerful hind legs/small, agile body/always alert
example of a predator?
lion
example of prey?
zebra
how do the features of predators help them?
- eyes set forward = spot prey, giving depth of field
- sharp teeth etc = pierce and tear flesh
- good senses = spot prey from far
- camo = to ambush prey (get close easily)
how do the features of prey help them?
- eyes at side = wide angle of view
- large eyes/smell = sense predator fast
- camo = avoid being seen
- nocturnal = avoid predators in day
- hind legs/agile/alert = ready to run away
what does the area of each bar represent in a pyramid of number?
number of organisms at each trophic level in a specified area
what does the area of each bar represent in a pyramid of biomass?
amount of organic matter (biomass) at each trophic level in a specified area
disadvantages of pyramids of biomass?
- organisms need to be collected and killed to measure dry mass
- difficult to catch and dry organisms
- biomass varies (tree in summer>winter)
- some organisms are omnivores and feed at more than one level
why is biomass lost?
- some plant material which can’t be digested leaves body as faeces
- some animal material can’t be digested e.g. bone, hooves, teeth
- biomass eaten by animals used in respiration to release energy and leaves as CO2 and water
what bodily functions cause biomass to be lost?
- biomass lost in faeces
- biomass lost in urine
- biomass lost provides energy for movement, growth etc
- energy from respiration transferred by heating surroundings
what % of energy is lost between trophic levels?
90% of energy lost as heat and in undigested materials
how is efficiency of energy transfer calculated? (%)
% = (energy transferred to next level/energy in previous level) x 100
(feeder/food) x100
what is a detritovore?
small animal which breaks down organic matter into small pieces; can help speed up decomposition
what are some examples of decomposers?
- bacteria
- fungi
- some insects
- snails
how do decomposers release nutrients?
enzymes!
how do decomposers use enzymes?
- fungus releases enzymes onto dead remains
- enzymes digest the dead matter, making it soluble
- soluble products are absorbed by fungus
what factors affect rate of decomposition?
- temperature
- oxygen availability
- water content
how does temperature affect rate of decomposition?
- too high = denatured enzymes
- prevents decomposition
- death of microorganism
how does oxygen availability affect rate of decomposition?
- O2 needed for respiration
- anaerobic conditions prevent most decomposition
- microorganisms cannot survive anaerobic conditions
how does water content affect rate of decomposition?
- little water would slow down reactions
- reduces/stops decomposition
how is rate of decay calculated? (g/day)
g/day = change in mass/time
what % of carbon dioxide does the atmosphere contain?
0.04%
what is carbon used for?
photosynthesis
how do animals get carbon?
by eating plants
how is carbon returned to the atmosphere?
by respiration and combustion
what three cycles are important for living organisms?
- water cycle
- carbon cycle
- nitrogen cycle
what % of nitrogen does the atmosphere contain?
78%
what is nitrogen found in, besides the atmosphere?
the soil
what do animals need nitrogen for?
protein-synthesis
what can bacteria do to plants and animals?
decompose them
what are denitrifying bacteria?
are in the soil breaking down nitrates, releasing nitrogen into the air
what are nitrogen fixing bacteria?
convert nitrogen gas into a useable form for the plants
what are nitrifying bacteria?
convert the ammonia (in urine) to nitrates
what do life forms use nitrogen to make?
proteins and DNA
what are some fixed forms that nitrogen is useable for plants and animals as?
nitrate ions, ammonia and urea
what can lightning do to nitrogen gas?
enormous amounts of energy from lightning can break nitrogen gas molecules, allowing it to combine with oxygen to form nitrogen oxides, which then dissolve rain to form NO3
what happens to NO3?
NO3 enters the soil and is absorbed by the plants through the roots, the plant uses the nitrogen to make proteins
what happens when nitrogen gas enters the soil?
nitrogen gas can enter the soil; nitrogen-fixing bacteria can turn nitrogen gas into nitrates
what is the name of the process of when nitrates in the soil are made using nitrogen gas from the air?
nitrogen-fixation
where are nitrogen-fixing bacteria found?
nitrogen-fixing bacteria found in the soil live in root nodules of leguminous plants (e.g. peas, beans and clover)
what do primary consumers eat?
they are herbivore animals that eat plants and digest the plant proteins and use the products (amino acids) to make their own proteins
how does decomposition involve nitrogen?
when animals die, decomposer bacteria break down proteins in the dead organism, releasing nitrates back into the soil, the plants absorb the nitrates
what does denitrifying bacteria do?
denitrifying bacteria in the soil break down nitrates and release nitrogen back into the air; this process is called denitrification
what is water important for?
- maintaining habitats
- allowing nutrients to flow between organisms and the environment
- survival of organisms
what happens to water during evaporation?
- water turns from liquid to gas when it evaporates
- energy from the sun can evaporate water e.g. ponds, oceans etc
what happens to water during condensation?
- after evaporation, water can cool and convert from gas to liquid (often forming clouds)
what happens to water during transport?
- water within clouds can be blown many miles by strong winds and so is transported to other areas
what happens to water during precipitation?
- precipitation occurs when rain, snow, hail and sleet fall from the sky
what happens to water during surface run-off?
- much water will be absorbed into the ground after precipitation but if a large amount falls or the ground is already wet, some water can run along ground surface
what happens to water during infiltration?
- occurs when water that has fallen as precipitation is absorbed into ground, this can be stored within underground rocks called aquifers
what happens to water during transpiration?
- plants need to maintain a constant stream of water to their leaves for photosynthesis, support and transport of minerals, they allow some water to evaporate as water vapour from their leaves so that more water is continuously ‘pulled’ to their leaves from the soil
describe the key points of the carbon cycle
- ‘powered’ by photosynthesis; green plants use carbon from CO2 to make carbohydrates/fats/proteins
- eating passes carbon compounds in plant along animals in food chain/web
- plant/animal respiration releases CO2
- plants/animals die and decompose or killed/turned into useful products
- during decomposition, broken down by microorganisms which release CO2 in respiration
- some useful plant/animal materials e.g. wood are burned (combustion); releases CO2 back into air
- decomposition means habitats maintained e.g. nutrients returned to soil, waste material e.g. dead leaves don’t just pile up
describe the key points of the nitrogen cycle
- plants get nitrogen from soil; nitrogen in air turned into nitrates before use; nitrogen compounds pass along food chains (animals eat plants and eachother)
- decomposers break down proteins in rotting plants/animals and urea in animal waste into ammonia which goes on to form ammonium ions; this returns nitrogen compounds to soil
- nitrogen fixation is process of turning N2 from air into nitrogen compounds in soil
describe the two main ways nitrogen fixation can happen
- lightning; so much energy in bolt of lightning that it’s enough to make nitrogen react with oxygen in air to give nitrates
- nitrogen-fixing bacteria in roots and soil
what types of bacteria are involved in the nitrogen cycle?
- decomposers
- nitrifying bacteria
- nitrogen fixing bacteria
- denitrifying bacteria
where do nitrogen fixing bacteria live?
- some live in the soil
- others live in nodules on roots of legume plants e.g. peas/beans
what are legume plants good at doing due to nitrogen fixing bacteria living in their nodules?
putting nitrogen back into the soil
how would you describe the relationship between legume plants and nitrogen fixing bacteria?
mutualistic
- bacteria get sugars/food from plant and plant gets nitrogen compounds from bacteria to make into proteins
describe the key points of the water cycle
- sun makes water evaporate from land/sea, turns into water vapour
- water evaporates from plants via transpiration
- warm water vapour carried upwards, when it gets higher it cools and condenses to form clouds
- water falls from clouds as precipitation and returns to land/sea
- flow of fresh water through water cycle allows nutrients to be transported to different ecosystems
what are the different levels within an ecosystem?
- individual
- population
- community
- ecosystem
what might plants compete for?
- light
- space
- water
- minerals/nutrients
what might animals compete for?
- space/territory
- food
- water
- mates
what abiotic factors may affect communities?
- temperature
- moisture level
- light intensity
- pH
what biotic factors may affect communities?
- availability of food
- number of predators
what are two types of interdependent relationships?
- mutualistic relationships
- parasitic relationships
